in 1823 he took a license degree in mathematics at Sorbonne University. He then became the private secretary of a field marshal who required assistance in writing his memoirs. This position must have left Cournot with considerable time for his own pursuits, for in the course of his ten years in the field marshal's employment he took two doctoral degrees, one in mechanics and one in astronomy. In addition, he published a number of articles and even acquired a degree in law.

Cournot was mainly a mathematician, but did have some influence over economics. His theories on monopolies and duopolies are still famous. In 1838 the book Researches on the Mathematical Principles of the Theory of Wealth was published, in which he used the application of the formulas and symbols of mathematics in economic analysis. This book was highly criticized and not very successful during Cournot's lifetime, and he did try to rewrite it twice, but it still has influence in economics today. Today many economists believe this book to be the point of departure for modern economic analysis. Cournot introduced the ideas of functions and probability into economic analysis. He derived the first formula for the rule of supply and demand as a function of price and in fact was the first to draw supply and demand curves on a graph, anticipating the work of Alfred Marshall by roughly thirty years. The Cournot duopoly model developed in his book also introduced the concept of a (pure strategy) Nash equilibrium, the Reaction function and best-response dynamics.

Cournot believed that economists must utilize the tools of mathematics only to establish probable limits and to express less stable facts in more absolute terms. He further held that the practical uses of mathematics in economics do not necessarily involve strict numerical precision.

Today, Cournot's work is recognized in econometrics. He was also a teacher of political economy and mathematics to Auguste Walras, who was the father of Léon Walras. Cournot and Auguste Walras persuaded Léon Walras to try political economics. Cournot is also credited to be one of the sources of inspiration for Léon Walras and his equilibrium theory.